1. Field of the Invention
The present invention relates to a user input device and, more particularly, to a user input device for a computer system.
2. Description of the Related Art
User input devices for computer systems can take many forms. Two forms of user input devices of interest are touch screens and pen-based screens. Touch screens provide a user""s input by way of a user touching a display screen with one""s finger. Pen-based screens provide a user""s input by way of a user touching a display screen with a stylus or pen.
One conventional approach to providing touch or pen-based screens is to overlay a resistive or capacitive film over the display screen. One problem of the conventional film approach is that the films are easily damaged. Another problem with the conventional film approach is that the cost of this approach tends to be too expensive for standard size or larger display screens because it scales quadratically with area. Another problem of the conventional film approach is that the largely translucent film is laid over the display screen. The film thus causes the display screen to appear dimmed. To compensate, the display screen could offer a greater intensity of light output but such is not always sufficiently available. For example, in the case of portable computers, additional light intensity is usually not available and, if it were, it would lead to additional power consumption that strains the battery of the portable computer.
Another approach to providing touch or pen-based screens is to use banks of infrared Light Emitting Diodes (LEDs) to provide light and a corresponding bank of phototransistors to detect the light. A major problem of the conventional light-based approach is that it requires a large number of components. The components are also too large for use on portable computers. Another problem with the conventional light-based approach is that it is unable to provide the high resolution needed for pen-based screens. Additionally, the conventional light-based approaches are expensive given the large number of components required.
Another approach to providing touch or pen-based screens is to use a bundle of fiber optic cables, a liquid crystal display (LCD) as a controllable mask, and a multiplexing scheme. Such an approach is described in U.S. Pat. No. 5,196,836. Here, although only a single light emitter is used, the spreading of the light output from the fiber optic cables is severe such that controllable LCD masks are needed to sequentially isolate light output from only one fiber optic cable at a time. The reception of the light from an isolated fiber optic cable is also isolated on the reception side. Given this arrangement, the system has to scan through each of the fiber optic cables using the multiplexing scheme which makes the approach very slow. Furthermore, this approach cannot yield high resolution needed for pen-based screens and is also rather expensive to fabricate.
Thus, there is a need for improved user input devices that can provide high resolution at moderate cost.
Broadly speaking, the invention relates to a user input device for an electronic device that provides positional information using a grid of light. The grid of light is produced and processed using waveguides that direct the transmission and reception of light. Optionally, optics may be used to enhance the operation of the user input device. The user input device is particularly suited for use as a user input device for a computer system or the like.
The invention can be implemented in numerous ways, including as an apparatus, a system, and a method. Several embodiments of the invention are discussed below.
An apparatus according to one embodiment of the invention includes: a light source; a transmission waveguide portion optically coupled to receive light from the light source, the transmission waveguide portion including a plurality of light transmission waveguides that produce a first set of light beams in response to the light received from the light source, and the first set of light beams emanate from the light transmission waveguides in a first direction; a reception waveguide portion spaced apart from the transmission waveguide in the first direction, the reception waveguide portion including a plurality of light reception waveguides for receiving the first set of light beams emanating from the light transmission waveguides; and a light detector optically coupled to the reception waveguide portion to receive the light from the light reception waveguides of the reception waveguide portion, the light detector measures light intensity of the light from the light reception waveguides of the reception waveguide portion. The embodiment may further include lenses optically positioned proximate to the transmission waveguide portion to collimate the first set of light beams emanating from the light transmission waveguides towards the corresponding light reception waveguides of the reception waveguide portion.
As an input device for an electronic device another embodiment of the invention includes: at least one light source; a light detector to detect light intensity at a plurality of light detecting elements; and a lithographically defined waveguide structure including a plurality of waveguides. The light source couples light into a first set of the waveguides of the waveguide structure and the waveguide structure produces a grid of light beams from the light coupling into the waveguides. The grid of light beams traverse an input area and are then directed to the light detector by a second set of the waveguides of the waveguide structure.
As a method for determining a user""s input with respect to an input device, an embodiment of the invention includes the operations of: providing a source of light; producing a plurality of parallel light beams from the source of light; simultaneously directing the parallel light beams across an input area of the input device, the input area being positioned with respect to the input device; simultaneously receiving certain of the parallel light beams after having crossed the input area; determining light intensity for each of the parallel light beams received; and determining whether there is a user""s input with respect to the input area based on the determined light intensity values.
The advantages of the invention are numerous. One advantage of the invention is that high resolutions are obtainable. Another advantage of the invention is that the cost of the input device is moderate and significantly lower than conventional designs because cost scales linearly with perimeter, thus making the input device especially beneficial for normal and large size display screens. Still another advantage of the invention is that display screen intensity is not hindered. Yet another advantage of the invention is that the input device requires few components which are relatively small, inexpensive, and easily assembled onto two-dimensional surfaces.
Other aspects and advantages of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.